Countdown in the Deadly Apartment

I move into an old apartment. When handing over the unit, the landlord only gave me one key, a clock with no hands, and one warning: "Do not touch the key, do not open any door before the clock chimes three times." The apartment only has an entrance door and no windows. I check the key every day to confirm it sits on the entryway tray, and I have never touched it. The clock stayed completely still and made no sound, so I gradually let my guard down. Late at night on the seventh day, the clock suddenly chimed its first ring, sharp and piercing. I panicked instantly, instinctively grabbed the key from the tray, wanting to open the door and escape, only to find the key would not fit into the lock at all. When the second chime rang, I saw red liquid seeping through the gap under the entrance door. The moment the third chime fell, everything went black. I lost complete consciousness and never woke up again. Please deduce: the purpose of the clock, the landlord's identity, the secret of the key, the origin of the red liquid, the reason I could not open the door, and the truth of my death (six core interlinked truths, no irrelevant settings).